Recently, with the rapid miniaturization of semiconductor integrated circuits, requirements for CD control of transcription patterns are becoming increasingly strict. Causes of CD variation of transcription patterns may be categorized roughly as mask-derived, exposure apparatus-derived, and resist-derived. For example, when shortening of exposure wavelengths is pursued for further miniaturization of semiconductor integrated circuits, the rate of CD variation derived from the flare of a projection optical system (exposure light diffusely reflected by a projection optical system) becomes relatively larger. This is because the flare is in almost inverse proportion to the square of the wavelength.
For example, the wavelength used in extreme ultra violet lithography (EUVL) emerging as lithography technology of next generation is smaller than the wavelength used in ArF lithography by at least one digit. Therefore, EUVL generates a flare which is larger than that in ArF lithography by about two digits. Previously, extensive time was taken for accurate flare calculation. Furthermore, due to inaccurate flare calculation, unexpected patterns were formed on substrates in some cases despite flare correction. Therefore, fast calculation of accurate flare values has been sought.